This invention relates generally to tools for picking locks, such as are used by locksmiths and lock manufacturers to assist the owner of a lock who has lost the key thereto. The invention particularly concerns a tool for picking a lock of the axial pin tumbler type having its tumblers arranged in a coplanar configuration.
Many axial pin tumbler locks have a cylinder within which tumblers are slidable in a longitudinal direction, i.e., parallel to the axis of the cylinder. In a large proportion of such locks, the tumblers are arranged in a circular pattern, and cylindrically shaped, or so-called circular, keys are required to operate them. The art has developed a number of picking tools to open that type of lock when the owner of the lock has lost his keys. Such picking tools are characterized by cylindrical symmetry.
Recently a much improved type of axial pin tumbler lock has been developed, and is disclosed in co-pending U.S. patent application Ser. No. 283,226, now U.S. Pat. No. 4,446,709, which is assigned in common with the present application. The preferred form of the new lock has its tumblers arranged in two parallel rows of coplanar tumblers, rather than in a circular pattern. Consequently, the conventional type of picking tool, which has its tumbler probes arranged in a circular grouping, will not work with such locks. Such picking tools are exemplified by the disclosures of U.S. Pat. Nos. 3,251,206, 3,270,538, and 3,149,487, and the "Pickmaster" pick (Custom Security Products, Inc.).
A problem in providing a picking tool for a lock of the foregoing type is posed by the need to provide for torquing of the lock cylinder, an important part of the picking technique, in the absence of the center post of the circular key-type lock. Previously, other types of locks, lacking a torquing point for engagement with the tool having the picking probes, were picked with the aid of a second tool or instrument, which was used to apply torque. Such technique, necessitating the simultaneous operation of two tools, is more difficult and requires greater skill. It would be a decided advantage to provide a picking tool which would accomplish both the probing and the torquing functions in one tool.
The lock of the foregoing type also presents a space problem, in that the spacing between rows of tumblers is small, with a correspondingly narrow keyway, and it is through such narrow space that the pick probes must enter. In order to apply a torque to the lock cylinder, it is necessary to provide for engagement of a torquing member with a lock part utilizing for entry into the lock whatever space is afforded in the keyway after insertion of the probes, while permitting suitable operation of the probes at the same time.